Artificial cardiac valves can comprise one, two, or more cusps having paired protrusions for fastening in the valve casing. During the valve operation, the protrusions experience a maximal mechanical loading.
Known is the method for manufacturing a cusp for an artificial cardiac valve made of titanium alloy with a coating made of pyrocarbon (RU Patent No. 2012284, 1994). However, the cusp made of two-layer material does not possess sufficient reliability when operating continuously for a long period of time. Moreover, in mounting the cusp protrusions in sockets of the casing, metal-to-metal friction problems arise.
Also known is a method for manufacturing the cusp by producing the pyrocarbon layer of controllable thickness on the surface of a graphite substrate by means of: deposing it, when decomposing carbon compounds from a gaseous stream in a through-flow reactor; separating subsequently the pyrocarbon layer from the substrate; and further processing mechanically pyrocarbon in order for shaping thereof in the form of a cardiac valve cusp (U.S. Pat. No. 6,274,191, 2001). The disadvantages of the method are its long duration, labor intensity, and the mechanical processing being performed manually, particularly at the final stage.
Known are methods for manufacturing the valve cusps from materials made on a polymer base. According to SU Inventor Certificate No. 1144216, 1987, cusps are manufactured of organic-silicon rubber reinforced by threads made of the same material. The RU Patents Nos. 2057494, 1996 and 2153887, 2000, describe methods for manufacturing cusps from polyester urethane. In the first instant, the cusp material includes additionally reinforcing fabric. In the second instance, the method provides for modifying the cusp surface using the pulse plasma spraying of carbon.
All the described methods are time-consuming and expensive, and the material of the cusps made by such methods does not keep mechanical properties and hemo-compatibility for a long time, as well as does not permit for checking for a condition of the artificial cardiac valve without surgical intervention.